Problem: playbooks/archivematica doesn't explain how to deploy QA

[sevein]

As f80bf57, if someone tries to deploy Archiveamtica using the deploy-pub/playbooks/archivematica it's unclear for a newcomer if stable or qa branches are being deployed. This just beat @mcantelon which is a sign that we're doing a poor job explaining it.

I suggest to have two environments:

• deploy-pub/playbooks/archivematica
• deploy-pub/playbooks/archivematica-qa

Or we could do a better job in the README file explaning how to download the right branch of the AM role (e.g. qa/1.7.x branch targets AM 1.7 and so on) and the right vars file.

[mcantelon]

Having the two environments might be easiest in terms of maintenance (compared to branches), and stuff from the qa could conceivably symlink to non-qa. README explanation of tweaks to make for qa version works too, though.